Toto Ultimate bowl level low after replacing fill valve

I used a Korky universal fill valve replacment in my Toto Ultimate toilet. The replacment fixed my original problem, which was that the valve sputtered and shut on and off while filling the tank. However, the water level in the bowl is too low now after flushing. If I hold down the handle, the bowl fills to the normal level. The water fill hose is clipped to the overflow tube and I can see that water is flowing steadily into the tube while the tank if filling. But it seems like the water flowing from beneath the fill valve cap fills the tank before enough water flows into the bowl through the overflow tube. The fill hose is not kinked and water flows through it freely, so I don't think it is obstructed. Could this be because I used the universal Korky fill valve instead of the one made specifically for Toto toilets?

If the fill valve refills the tank too quickly, it will not flow enough water through the refill tube to also refill the bow. The only remedies are to get a slower fill valve with full volume to the refill tube, or try shutting the water supply to yours so the tank fills slower, but the refill tube still delivers a full stream.

If the fill valve refills the tank too quickly, it will not flow enough water through the refill tube to also refill the bow. The only remedies are to get a slower fill valve with full volume to the refill tube, or try shutting the water supply to yours so the tank fills slower, but the refill tube still delivers a full stream.​

Thanks for the suggestions. I will try partially shutting the water supply to see if that helps. If that fails, my plan is put the old fill valve back but replace the cap assembly with the one from the new valve. If that fails, I'm going to order a 528T fill valve. Beyond that, I'm out of ideas.

Regarding the vaIve filling the tank too quickly, I am wondering if that is what Korky means by "Higher refill ratio for optimum performance in TOTO toilets" in the description of the 528T fill valve (I used the 528). As pointed out in other threads, Terry has reported success using the 528 in Toto toilets, but the question of what the difference is between the 528 and 528T seems to remain unanswered.

The easiest fix is always to just replace the $1.99 assembly cap.
It takes less than a minute, and costs the lest. ​

Granted I should have done that to begin with, but keep in mind that I just replaced the whole valve, so I now have a brand new assembly cap in my toilet. So assuming that the brand new cap is not somehow defective, my question is whether the valve I installed (Korky QuietFill Fill Valve p/n: 528) is incompatible with my Toto Ultimate and causing the water level in the bowl to be too low after flushing?

I also installed the Korky Quiet Fill in one of my toilets in my camp last year. The water is gravity fed and filtered, with about 15 lbs. pressure at the faucets, and the screen inside the Quiet Fill is clean.

I noticed that the water coming in through the refill tube is very slow as compared to a Fluidmaster 400A or the Mansfield 09 in the shed bathroom. Near the end of the fill, the water coming out of the refill tube increases by quite a bit, to the point where I can hear the water trickling down the jet passage in back of the bowl. It seems to happen just as the water is lifting the float that's hidden under the cap.

It is not causing an issue because the bowl fills to its correct level (it's a big tank). But, is this normal for this type of valve? If this was a 1.6 tank, I would probably having the same issue as Ned is reporting.

I notice no difference in the flow in my Toto at home which is on municipal water and has the same valve (with the G-Max cover).

I had the exact same problem as ned after replacing the fill valve in my ultramax w/ the korky 528. The bowl wouldn't fill all the way (was dependent on how long I held the flush lever down). The water level in the tank was exactly at the mark. I replaced the entire fill valve assembly including the black tube that fills the bowl. That didn't work. I then replaced the assembly cap w/ a new one from my Toto dealer. Still the same problem. Finally I replaced the entire fill valve with the korky 528T ("for Toto"). The flow rate through the little black tube into the bowl is much higher than on the 528. The water level in the bowl fills to the correct level regardless of how short/long I hold the flush lever down. So you need to use the Korky 528T, not the Korky 528.

I just replaced the sink in my bathroom along with both hot and cold water supply valves. To remove those valves, I had to shut off the water to my house. After removing them, I noticed that there was corrosion in both nipples, surprise surprise (the house has galvanized plumbing installed in the 1920's)! Got the sink working, but then, to my surprise, the tank on our Toto Aquia totally stopped filling after the next flush, and I mean not even a drop. Since I had just replaced two leaky valves in the wall, I went ahead and replaced the valve that fills the toilet as well. I cleaned out the corrosion, reapplied silicon tape, reattached the flexible supply hose and opened the valve. Still, nothing. I heard water entering the hose but it never made it into the tank.

According to my plumber, I am faced with the lovely Christmas eve chore of removing the tank from the Aquia just so that I can check the other end of the hose that feeds into the fill valve inside the tank. I am not looking forward to this, because Toto offers no instructions at all on how to service this model, not even to plumbers, and of course, they are closed for the holidays.

I imagine that this is not going to be as simple as using a screwdriver to remove both screws on the inside bottom of the tank. There are probably those nasty plastic nuts cemented on the bottom of the tank, which is of course virtually impossible to access without first changing into an elf. Anyway, my concern is that once I have the tank off, and I check the hose, if it is clear, I will not know what to do next. Is there anything about this toilet's fill valve that can be adjusted without removing everything? The fill valves of most toilets can be adjusted with a simple turn of a screw to modify the angle of the arm that attaches to the floater, but not the Aquia! Anyone have any suggestions before I remove the tank, knowing full well that I am going to have to put it back and risk creating leaks where none were before? If any one has a better diagnosis, second opinion or simpler solution, it would make a better Christmas gift than anything Santa could offer (other than a real live plumber who has got one of these in his own place...many experienced plumbers have no idea what they are getting into when confronted with the Toto Aquia and its lack of complete and accurate instructions).
Sure you all have better things to do than read toilet forums on Christmas eve, but in all honesty, Christmas probably gives the Superbowl halftime a run for its money on the national flush meter.
Joyeux NoÃ«l!
- Jonezen (for a bucket-less flush)

Not unusual to have flakes of corrosion or hard water deposits come loose when the water is shut off.

I don't see any apparent need to take the tank off the toilet - as you say, this just increases the risk of leaks and isn't really necessary.

I would disconnect the flexible supply line where it attaches to the fill valve at the bottom of the tank, then turn on the water to see if anything comes out (have a bucket handy!). If water comes out at a brisk pace, then the problem is the fill valve is plugged up. It may be possible to clean it out, but I don't know that model so can't say for sure. Would be best to replace it if it is plugged up.

On the other hand, if no or very little water comes out of the end of the supply line with the valve on the wall open, then obviously you have either a plugged flexible supply line or the supply valve itself is plugged up.

I had the same cutting-on-and-off problem with a Toto/Korky fill valve. Talking with the Korky customer service confirmed that I would need the 528T because of the fill ratio you described. But the replacement cap that Terry mentioned is the same for both valves, and since the toilet was less than a year old, Korky sent one in the mail for free. The new cap solved the problem. Putting your original fill valve back with the cap from the new one might do the job and save buying another fill valve.

I did have to remove the tank because the toilet has a sink three inches to the left of it, so there was no reaching the upper end of the valve from below. However, once I got it open, I saw that there was indeed a lot of sediment build-up that needed to be flushed out of the flexible pipe connector. I removed the washer, used Bar-Keeper's Friend cleanser (citric acid plus steel wool dissolved the corrosion without being abrasive) on the screw housings at the base of the tank, and cleaned both rubber gaskets and the two metal rings that sit atop them. Interestingly, I noticed that my plumber had inserted a spring loaded washer (an internal spring surrounded by a black rubber washer about a centimeter high) that he screwed down onto the brass stems that enter the tank from beneath on either side of the large central rubber gasket. I am not whether they came included with Toto's setup, but I have never had any leaks from below the tank, and wondered if this might be a helpful addition to any setup. One of them was worn, and so I simply replaced it. You can find them at The Home Despot for a dollar or two as part of a kit used to repairing Delta kitchen faucets of the one-handle varietal). I rinsed out both the fill valve and the drain pipe, then tightened the hell out of the brass screws as specified in many of the forums specific to the the Aquia model. The entire process took two and half hours, but I worked slowly and carefully out of concern for breaking something or having to redo it right after changing the sink.
Long story short, as soon as everything was back together, we were very pleased to hear the familiar music of fresh water flowing into the tank once again. And this morning when I checked the floor for puddles, I found none, so Santa must not have used the facilities, though he did stir things up a bit about the fireplace mantle.
Thanks once again to all three of you for taking time out of your special holiday to assist a fellow Left Coast Toto-Head Flush Meister. You have helped take a load off of all of us.
Warm regards and royal flushes....
Jonezen